Newbie Qs on stalls and spins

"Terry Bolands" wrote in message
om...
Wow, thanks for adding so much to the conversation.

You're welcome, and thank YOU very much for the same.

At least I have *some* posts in this thread with actual content. Too bad
you can't say the same.

You guys are challenging my understanding of landings :-)

The landing technique, as taught by many before us, is to
progressively increase elevator deflection to maintain zero vertical
speed. I suppose it is possible that you can reach max elevator
without reaching critical AOA. But I think that is unlikely, because
that would mean you will never be able to perform power-off stalls in
level unaccelerated flight.



"Peter Duniho" wrote in message ...
"Andrew Sarangan" wrote in message
1...
OK OK... What I meant was, every normal landing (other than short field
techniques) would involve a stall.

See George's post. Your modified statement is still incorrect.

Andrew Sarangan wrote:

You guys are challenging my understanding of landings :-)

The landing technique, as taught by many before us, is to
progressively increase elevator deflection to maintain zero vertical
speed. I suppose it is possible that you can reach max elevator
without reaching critical AOA.

Ah, yeah. See Cessna 177A. They had to add slots to the stab so the
tail wouldn't stall before the wing.

"Andrew Sarangan" wrote in message
om...
You guys are challenging my understanding of landings :-)

Challenge is good for the soul.

The landing technique, as taught by many before us, is to
progressively increase elevator deflection to maintain zero vertical
speed.

That's the ideal. In practice, it's nearly impossible to obtain exactly
zero vertical speed, and it's bad form for your vertical speed to go
positive (i.e. start to climb). In a properly executed landing, vertical
speed is always negative (i.e. a descent), and one typically reaches the
runway before reaching the critical AOA.

I suppose it is possible that you can reach max elevator
without reaching critical AOA.

Certainly once the main gear is on the ground, it is. I commonly continue
to increase elevator back pressure after touchdown, so as to allow the
nosewheel to touchdown gently, and may well reach max elevator travel before
allowing the nosewheel to touch. But this is a red herring in any case, as
there is no requirement nor even a recommendation to reach max elevator
travel during a landing.

But I think that is unlikely, because
that would mean you will never be able to perform power-off stalls in
level unaccelerated flight.

At least one plane does have this characteristic (Ercoupe). Landings in
that airplane, one in which it is impossible to stall (in level
unaccelerated flight, anyway, such as one would experience during a
landing), are pretty much just like landings in any other airplane.

A typical "normal" landing involves flying a slightly fast approach speed
(1.2 to 1.3 Vs0), and then flaring and touching down while still above Vs0.
One hopes that during the flare, airspeed is reduced to as close to Vs0 as
possible so as to minimize touchdown speed. In optimal conditions, a
well-executed landing will even be done with the stall warning going off.
But touchdown itself should still occur prior to the stall occurring (which,
of course, prevents the stall from occurring at all).

Bottom line: just as George said, "no normal landing involves a stall".

Pete

I suppose it is possible that you can reach max elevator
without reaching critical AOA. But I think that is unlikely, because
that would mean you will never be able to perform power-off stalls in
level unaccelerated flight.

The horizontal stabilizer and elevator are sized so that you can reach
max lift coefficient under the most extreme conditions, which will be
forward CG and in ground effect.

Since GE increases the stability of the aircraft, it is possible that
you could stall at altitude, but not close to the ground.

OK OK... What I meant was, every normal landing (other than short field
techniques) would involve a stall. I guess I have to be more careful in
my choice of words :-)

I was really astonished, the first time I landed as a passenger in a
small plane, to be told by the pilot that the horn that blared just
before touchdown was a stall warning. I assumed the pilot had made a
mistake (in his landing technique, not in his explanation for the
horn)!

all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

"Cub Driver" wrote

I was really astonished, the first time I landed as a passenger in a
small plane, to be told by the pilot that the horn that blared just
before touchdown was a stall warning. I assumed the pilot had made a
mistake (in his landing technique, not in his explanation for the
horn)!

all the best -- Dan Ford
email: (put Cubdriver in subject line)

But remember, stall horns are usually 8 mph before stall.
--
Jim in NC


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.797 / Virus Database: 541 - Release Date: 11/16/2004

"Morgans" wrote in message
...

"Cub Driver" wrote

I was really astonished, the first time I landed as a passenger in a
small plane, to be told by the pilot that the horn that blared just
before touchdown was a stall warning. I assumed the pilot had made a
mistake (in his landing technique, not in his explanation for the
horn)!

all the best -- Dan Ford
email: (put Cubdriver in subject line)

But remember, stall horns are usually 8 mph before stall.
--
Jim in NC

Careful, Jim. Depends on your flight regime. The stall horn is actually
set a couple of DEGREES above stall angle of attack. In the landing
configuration that may equate to about 8 mph, but that's not how it's set.

Shawn
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.797 / Virus Database: 541 - Release Date: 11/16/2004

"Morgans" wrote
But remember, stall horns are usually 8 mph before stall.

Section 23.207: Stall warning.

(c) During the stall tests required by §23.201(b) and
§23.203(a)(1), the stall warning must begin at a speed
exceeding the stalling speed by a margin of not less
than 5 knots and must continue until the stall occurs.

Peter Duniho wrote:

IMHO, it is generally poor technique to "fall" at all during a landing. One
exception is a short field landing where minimum airspeed is the highest
priority, even if it means a "firm" landing.

And, even with a short field landing, my aircraft is not stalled when flown
properly. I am likely to have a high enough descent rate for it to be a "firm"
landing; however, if I time the last burst of throttle correctly, even that
won't be the case.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.